Noise Levels in Downtown South San Francisco, South San Francisco, CA | Find Quiet Neighborhoods With Our Sound Map
58 dBA
Average noise across Downtown South San Francisco
Normal conversation an arm’s length away
2,712
Residents above the EPA 55 dBA threshold
86% of Downtown South San Francisco residents
72 dBA
Loudest residential point
City bus interior
This map shows modeled outdoor noise across Downtown South San Francisco at 100-meter resolution, combining road, aviation, and rail sources. Green areas measure below 45 dBA. Orange and red exceed the EPA's 55 dBA outdoor threshold linked to long-term health effects. Use the layer toggles to view each source on its own or all together.
Overall
Road
Rail
Aviation
Click the map to explore
35 dBa55 dBa (EPA limit)90+ dBa
3545557090
Quietest (dBA)Loudest
Colorblind friendlyoff
What the numbers sound like
30 dBAWhisper
40 dBASoft rainfall
45 dBAQuiet suburban street at night
50 dBAQuiet office
55 dBAEPA outdoor threshold: light traffic 100 ft away
60 dBANormal conversation an arm's length away
65 dBABusy restaurant
70 dBAHighway traffic 50 ft away
80 dBACity bus interior
Population Above the EPA Outdoor Threshold
The EPA's 55 dBA outdoor reference level is a common benchmark for residential noise exposure, especially for activity interference, annoyance, and long-term community noise concerns. About 2,712 Downtown South San Francisco residents, or 86.3%, live above that level. By land area, 91.2% of Downtown South San Francisco is above 55 dBA.
Average noise levels for Downtown South San Francisco residents, grouped by direction from the center of Downtown South San Francisco. Southern Downtown South San Francisco carries the highest population-weighted average; Western Downtown South San Francisco carries the lowest. Just 10% of residents in Western Downtown South San Francisco live in blocks above the EPA's 55 dBA threshold, a fifth of the share in Southern Downtown South San Francisco.
Central Downtown South San Francisco
59.1 dBA · Loud
Normal conversation an arm’s length away
95% of people above 55 dBA
QuietLoud
Southern Downtown South San Francisco
62.5 dBA · Loud
Busy restaurant
93% of people above 55 dBA
QuietLoud
Western Downtown South San Francisco
52.3 dBA · Moderate
Quiet office to normal conversation
10% of people above 55 dBA
QuietLoud
Southern Downtown South San Francisco sounds about 103% louder than Western Downtown South San Francisco to the human ear, a 10.2 dBA gap. Every 10 dBA roughly doubles perceived loudness. Within any of these directions, two homes a quarter mile apart can still differ by 10 or more dBA depending on how close they sit to a major highway.
How far back from Bayshore Fwy do you need to be?
Bayshore Fwy produces an estimated 79 dBA at its loudest centerline points. Noise drops logarithmically with distance, with the exact rate depending on what's between you and the road. Tree cover, walls, terrain, and pavement type all matter. At roughly a quarter mile back, traffic fades into the noise level of a soft rainfall.
At source
79 dBA
City bus interior
165 ft
64 dBA
Busy restaurant
330 ft
56 dBA
Quiet office to normal conversation
660 ft
48 dBA
Quiet office
¼ mile
39 dBA
Soft rainfall
½ mile
35 dBA
Soft rainfall
Calculated from the model's calibrated attenuation formula. About 2% of Downtown South San Francisco sits under tree canopy (much lighter than most neighborhoods) and roughly 72% is impervious surface like pavement and rooftops. Both are folded into the per-place decay rate above. Heavier canopy pulls noise down faster with distance; impervious surfaces slow the drop.
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Rail Noise
Active freight rail runs through parts of Downtown South San Francisco. For most blocks the rail-only contribution is small. Combined road-plus-rail noise rarely exceeds road noise on its own. The exceptions are the handful of blocks within roughly a quarter mile of the right-of-way during pass-through hours.
Use the Rail toggle on the map above to isolate rail's contribution from road and aviation.
Airport Noise
San Francisco International (SFO) sits southeast of Downtown South San Francisco. The U.S. Department of Transportation measures aviation noise around this airport directly, and the model uses those federal measurements rather than synthetic predictions.
Blocks under the approach and departure paths carry combined road-plus-aviation noise, with some exceeding 50 dBA on the map's Overall layer. Blocks on the opposite side of Downtown South San Francisco, particularly to the northwest, show no measurable aviation contribution. Use the Aviation toggle on the map above to isolate the airport's footprint.
How Noise Is Distributed Across Downtown South San Francisco
The bar chart below shows the share of Downtown South San Francisco residents in each noise band. About 9% of residents live below the EPA's 55 dBA threshold, and roughly 30% live in blocks above 60 dBA. Long-term exposure in that range is linked to elevated stress hormones and cardiovascular risk.
How Downtown South San Francisco Compares
Downtown South San Francisco sits the highest among the peer group. Below: how Downtown South San Francisco's average outdoor noise and share of residents above the EPA threshold compare with Paradise Valley, orange-park-south-san-francisco-ca, Edgemar-Pacific Manor, and Diamond Heights.
Average noise level (dBA)
Downtown South San Francisco's 58.5 dBA pop-weighted average is the highest among the peer group. California as a whole averages 54.0 dBA and the U.S. averages 52.0 dBA. Both are lower than Downtown South San Francisco because most of either area is rural land away from major roads.
Share of residents above 55 dBA
About 86.3% of Downtown South San Francisco residents live in blocks where outdoor levels exceed the EPA's 55 dBA threshold. That's more than any of its peer group. Measured by land area instead, 91.2% of Downtown South San Francisco's footprint sits above 55 dBA, against a California average of 36.0% and a national average of 28.1%.
What This Means if You're Moving to Downtown South San Francisco
Distance from highways matters more than the neighborhood name. Two homes in the same zip code can differ by 20 dBA if one sits 100 meters from Bayshore Fwy and the other 500 meters away. The model captures this at 100-meter resolution, so noise exposure changes block by block.
Tree canopy can help reduce modeled noise exposure. Roughly 2% of Downtown South San Francisco is under tree cover (much lighter than most neighborhoods), and the dominant land cover is medium-intensity developed land. Both are measured from federal USDA Forest Service and USGS satellite imagery at 30-meter resolution. Streets with 60% or higher canopy show 3 to 5 dBA lower noise than comparable streets with bare ground or pavement, which is why the per-place decay rate above already accounts for it.
Airport noise is directional. San Francisco International's approach paths concentrate aviation noise to the southeast. Neighborhoods to the northwest of downtown show no measurable contribution from the airport.
Sources & Methodology
The BestNeighborhood noise model is calibrated against nearly one million federal ground-truth measurements across four states. Road noise is computed from segment-level federal traffic data and propagated outward using physics-based acoustic decay, with attenuation rates that depend on the surrounding land cover.
All inputs are published federal datasets. Block-level noise is computed by combining road, rail, and aviation sound sources in the energy domain, the same physics used in professional environmental noise assessments. Read the full methodology.
